1.\" 2.\" Copyright (c) 2002 M. Warner Losh. 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.\" $FreeBSD$ 27.\" 28.Dd October 17, 2002 29.Dt DEVD 8 30.Os 31.Sh NAME 32.Nm devd 33.Nd "device state change daemon" 34.Sh SYNOPSIS 35.Nm 36.Op Fl Ddn 37.Sh DESCRIPTION 38The 39.Nm 40daemon provides a way to have userland programs run when certain 41kernel events happen. 42.Pp 43The following options are accepted. 44.Bl -tag -width indent 45.It Fl D 46Enable debugging messages. 47.It Fl d 48Run in the foreground instead of becoming a daemon. 49.It Fl n 50Do not process all pending events before becoming a daemon. 51Instead, call daemon right away. 52.El 53.Sh IMPLEMENTATION NOTES 54The 55.Nm 56utility 57is a system daemon that runs in the background all the time. 58Whenever a device is added to or removed from the device tree, 59.Nm 60will execute actions specified in 61.Xr devd.conf 5 . 62For example, 63.Nm 64might execute 65.Xr dhclient 8 66when an Ethernet adapter is added to the system, and kill the 67.Xr dhclient 8 68instance when the same adapter is removed. 69Another example would be for 70.Nm 71to use a table to locate and load via 72.Xr kldload 8 73the proper driver for an unrecognized device that is added to the system. 74.Pp 75The 76.Nm 77utility 78hooks into the 79.Xr devctl 4 80device driver. 81This device driver has hooks into the device configuration system. 82When nodes are added or deleted from the tree, this device will 83deliver information about the event to 84.Nm . 85Once 86.Nm 87has parsed the message, it will search its action list for that kind 88of event and perform the action with the highest matching value. 89For most mundane uses, the default handlers are adequate. 90However, for more advanced users, the power is present to tweak every 91aspect of what happens. 92.Pp 93The 94.Nm 95utility 96reads 97.Pa /etc/devd.conf 98and uses that file to drive the rest of the process. 99While the format of this file is described in 100.Xr devd.conf 5 , 101some basics are covered here. 102In the 103.Ic options 104section, one can define multiple directories to search 105for config files. 106All files in these directories whose names match the patten 107.Pa *.conf 108are parsed. 109These files are intended to be installed by third party vendors that 110wish to hook into the 111.Nm 112system without modifying the user's other 113config files. 114.Pp 115All messages that 116.Nm 117receives are forwarded to the 118.Ux 119domain socket at 120.Pa /var/run/devd.pipe . 121.Sh SEE ALSO 122.Xr devctl 4 , 123.Xr devd.conf 5 124.Sh AUTHORS 125.An M. Warner Losh 126